Commonly assigned U.S. Pat. No. 4,603,166 discloses polyphthalamide compositions which, when filled with glass fibers and molded, have heat deflection temperatures at 264 psi, determined according to ASTM D-648, above about 245.degree. C. Included are compositions comprising recurring terephthalamide and adipamide or terephthalamide, isophthalamide and adipamide units. As disclosed therein, such compositions, including particulate- and fiber-filled compositions, exhibit desirable thermal properties including heat deflection temperature, high tensile strength and flexural modulus and are useful in various applications including preparation of molded articles, fibers, and laminates.
Commonly assigned U.S. Pat. No. 4,617,342 and commonly assigned, U.S. Pat. No. 4,863,991, to Poppe et al., and published European Patent Application No. 84300745.1 (Publication No. 0122688), disclose polyphthalamides which, when filled with glass fibers, have heat deflection temperatures at 264 psi, determined according to ASTM D-648, above 240.degree. C. Compositions according to U.S. Pat. No. 4,617,342 are prepared from dicarboxylic acid compounds comprising terephthalic acid and isophthalic acid compounds in a mole ratio of 80:20 to about 99:1 and diamines comprising hexamethylene diamine and trimethylhexamethylene diamine in a mole ratio of about 98:2 to about 60:40. Compositions taught in U.S. Pat. No. 4,863,991 are based on terephthalic acid and isophthalic acid compounds in a mole ratio of about 70:30 to about 99:1 and hexamethylene diamine. Such compositions have utility in various applications, the neat and fiber-filled compositions being particularly suited for molding applications.
For certain end uses it would be desirable to modify certain properties of polyphthalamides such as those described above. In particular, it would be desirable to provide polyphthalamides with improved properties such as lower moisture absorption and improved heat deflection temperatures. Reduced moisture absorption is important because it can lead to better retention of mechanical properties by articles fabricated from polyamides when exposed to wet or humid environments. Such improvements would lead not only to improved performance of products fabricated from such resins in existing end uses, but also utility in additional applications with more stringent requirements. Examples of specific applications for such polyphthalamides where the above improvements would be beneficial include many injection molding and engineering applications, such as electrical and electronic connections, pump housings, and automobile under-the-hood and trim parts, especially those under-the-hood parts which are exposed to higher than ambient temperatures.
In general, it is known that modification of polymer properties may be achieved in various ways. Modification of the molecular structure of a given composition through the use of additional monomers in polymerization can lead to desirable improvements in some properties. However, the same often are accompanied by loss of other desirable properties and use of additional monomers is not always practical due to process considerations. Addition of other materials to a polymeric composition may lead to property improvements without complicating a polymerization process; however, improvements in some properties often are achieved at the expense of other properties. Blending a given polymer with one or more other polymers may give blends with combinations of properties intermediate those of the individual components; however, processing requirements often limit the number of candidates that can be blended with a given polymer in an attempt to attain desirable property modifications and properties of a blend may or may not reflect those of its components depending on compatibility of the components with each other, reactivity thereof under blending or processing conditions and other factors.
Patents disclosing polymers containing meta-xylylene diamine are discussed below.
U.S. Pat. No. 2,766,221 discloses polyamides of meta-xylylene diamine and aliphatic dicarboxylic acids of 6 to 10 carbon atoms useful in the production of films, molded articles and the like.
U.S. Pat. No. 2,766,222 discloses polyamides of meta-xylylene diamine and isophthalic acid and mixtures of isophthalic acid and terephthalic acid.
U.S. Pat. No. 4,937,276 discloses polyamide molding compositions containing the polycondensation product of terephthalic acid, adipic acid and hexamethylenediamine reinforced with glass fibers and stabilized with a mixture of copper-, halogen- and phosphorus-containing compounds.
U.S. Pat. No. 4,018,746 discloses amorphous unfilled polyamides prepared by polycondensing meta-xylylene diamine preferably present at 50 to 85 percent of the total amine content, which may optionally be partially substituted by paraxylylene diamine, at least one straight chain aliphatic diamine, at least one unsubstituted aromatic dicarboxylic acid and at least one aliphatic saturated dicarboxylic acid.
U.S. Pat. No. 3,962,524 discloses a glass fiber reinforced polyamide resin composition comprising a polyamide resin obtained by the condensation reaction of xylylene diamine with an aliphatic straight-chain dicarboxylic acid having 6 to 12 carbon atoms and 5 to 50 weight percent of glass fibers.
U.S. Pat. No. 3,968,071 discloses a polyamide molding composition of 3 to 97 weight percent of a meta-xylylene diamine and adipic acid polyamide, 97 to 3 weight percent of nylon 6,6 and glass fibers.
Polyamide resins containing moieties of AA and MXDA are available from Mitsubishi Gas Company as RENY-6001, an unfilled polyamide having a molar ratio of AA:MXDA of 50:50 and RENY-1002, a nucleated and 30 wt % glass fiber-filled polyamide having a molar ratio of AA:MXDA of 50:50. These polymer resins have 100 mole percent of their aliphatic moieties provided by the dicarboxylic acid component of adipic acid and 100 mole percent of their aromatic moieties provided by the diamine component of meta-xylylene diamine. The HDT of these resins were measured at 264 psi according to ASTM D 648 and found to be 69.degree. and 88.degree. C. for the neat and filled resins, respectively.
Although the above patents disclose polyamides prepared from dicarboxylic acids and meta-xylylene diamine, none discloses the invented crystalline polyamide compositions comprising recurring units based on terephthalic acid, adipic acid, hexamethylene diamine and meta-xylylene diamine wherein about 10 to about 30 mole percent of the aliphatic moieties are provided by the dicarboxylic acid components and about 10 to about 30 mole percent of the aromatic moieties of the polyamide compositions are provided by the diamine components, nor the desirable thermal and mechanical properties exhibited by such compositions. Surprisingly, polyamide compositions of the present invention filled with fibrous and particulate fillers have excellent heat deflection temperatures of greater than 250.degree. C. when molded.
An object of this invention is to provide an improved polyamide composition. A further object is to provide a polyphthalamide composition having utility in injection molding and other applications. A still further object of the invention is to provide filled polyphthalamide compositions having improved heat deflection temperature and lower moisture absorption resulting in improved retention of mechanical properties when used in applications involving exposure to wet or humid environments.
The objects of this invention can be attained by providing a crystallizable resinous polymer comprising recurring units of dicarboxylic acid moieties derived from terephthalic and adipic acid and diamine moieties derived from meta-xylylene diamine and an aliphatic diamine having 4 to 20 carbon atoms and to fibrous and particulate filled compositions of the resinous polymers.
Generally, such polyphthalamides have melting points of about 280.degree. to about 315.degree. C. and a glass transition temperature ("Tg") of about 105.degree. to about 125.degree. C. The invented polyamides and polyamide composition provide good mechanical properties when used in applications involving exposure to wet or humid environments.